DROWN (OpenSSL vulnerability) - CVE-2016-0800

Advisory ID: 16-0008
Publish Date: 2016-03-07
Revision: 1.0

Summary

On March 1, 2016, the OpenSSL Software Foundation published news about a vulnerability in OpenSSL that would put servers running SSLv2 at risk of man-in-the-middle (MITM) attacks (see External References section for more information).

The following CVE is associated with this vulnerability:
CVE-2016-0800

Detailed Description

According to NVD and CVE-2016-0800:

The SSLv2 protocol, as used in OpenSSL before 1.0.1s and 1.0.2 before 1.0.2g and other products, requires a server to send a ServerVerify message before establishing that a client possesses certain plaintext RSA data, which makes it easier for remote attackers to decrypt TLS ciphertext data by leveraging a Bleichenbacher RSA padding oracle, aka a "DROWN" attack.

It allows SSLv2 connections. This is surprisingly common, due to misconfiguration and inappropriate default settings. Our measurements show that 17% of HTTPS servers still allow SSLv2 connections.

or:

Its private key is used on any other server that allows SSLv2 connections, even for another protocol. Many companies reuse the same certificate and key on their web and email servers, for instance. In this case, if the email server supports SSLv2 and the web server does not, an attacker can take advantage of the email server to break TLS connections to the web server. When taking key reuse into account, an additional 16% of HTTPS servers are vulnerable, putting 33% of HTTPS servers at risk.

The risk to products where SSLv2 has been permanently disabled, or SSLv2 has been disabled through configuration is lower than those where SSLv2 is enabled.

Mitigation / Recommended Action

SSLv2 is in an insecure protocol and should be disabled on all systems (not just Mitel products and services). The importance of doing so being greater for systems accessible from untrusted environments. Additional attention should be extended in the rare case that the private keys of Mitel products or servers are installed on other systems.

Customers are also advised to update products and services in their environment to the latest releases to address resolved security issues.

Mitel will continue to investigate and provide additional recommendations or solutions as might be warranted.